Retractable undercarriage for aircraft



y 1941- F. MEYER ETIAL 2,240,892

RETRACTABLE UNDERGARRIAGE FOR AIRCRAFT Filed April 15, 1959 In vemora .fiznz Meyer, flaiz Ma ir Aflorneva Patented May 6, 1941 2,240,892 RETRACTABLE UNDEBCABRIAGE FOR. AIRCRAFT Franz Meyer and Fritz Maire, Bradenburg, Havel,

ignors to Arado Flugzeugwerke Germany, Gesellschalt mit beschraenkter Haftung, Babelsberg, near Berlin, Germany, a company of Germany Application April 15, 1939, Serial No. 26,136 In Germany May 18, 1938 Claims- (01. 244102) ditional sources of trouble. -With manually operable undercarriages it is necessary to interpose transmission means between the operating lever and theundercarriage. The whole arrangement is thereby rendered very complicated, and the retraction and protruding operations occupy a relatively long time.

The invention avoids the described drawbacks and renders possible rocking of the undercartriage with quite small expenditure of power and with the aid of a simple mechanism. According to the invention, on each of the rock shafts there is so arranged a lever connected by way of a rope with a tension means, for example, a rubber tension device, that, in any given position which the undercarriage assumes during the retraction and protrusion, there is abalance between the moments caused by the weight of the halves of the undercarriage and thoseset up by. the tension means about the rocking .axis.

Two embodiments of the invention are illustrated in the accompanying drawing.

Fig. ishows in perspective one half of the undercarriage, namely, the port side, together with the rocking mechanism constructed according to the invention.

Fig. 2 shows to a larger scale a rocking mechanism together with a locking device partly in elevation and partly in section through the easing as viewed in the direction opposite the direction of flight.

In Fig. 1, which shows schematically an undercarriage constructed according to the invention with its actuating mechanism, 1 denotes the operating lever; 2, 3 and 4 are parts of the linkand-lever mechanism; 5 is the rock shaft of the half 5 of the undercarriage.

' a pulley l1 and which is connected with a rubber tension member 9.

The operation of the construction according to Fig. 1 is as follows:

When the undercarriage 5 is protruded, the

tion opposite the direction of flight, that is, in'

the direction of the arrow in Fig. 1. Then, by way of the link-'and-lever connections 2, 3, 4, the lever l0 and thus the shaft 5 and the undercarriage half 6 are moved in the direction of the lower arrow of Fig. 1. In this rocking movement the leverage of the power exercised by the rubber tension member 9 on the lever I in relation to the rock shaft 5 is increased inthe same proportion as that in which the leverage of the centre of gravity of the undercarriage half 6 relatively to the rock-shaft 5 is increased. The rubber tension member 9 is'pretensioned in correspondence with the weight of the halves of the undercarriage, so that, in any given position of retraction or protrusion of the undercarriage, there is a balance of moments about the rock shaft 5. For operation there is required to be exercised on the lever I only the force necessary .,to overcome the small frictional forces in the bearings of the mechanism. One complete stroke of the lever l corresponds to the entire inward or outward travel of the undercarriage.

In the construction illustrated in Fig. 2, there is arranged on the rock shaft a casing l2, which receives the locking device for the undercarriage consisting of theparts i4, i5, 22, 29, I6, 28. In a lug 2| connected with the casing l2 there is pivotally mounted a cap-like part I3 connected to the rod or link 4 at the point 20. Further, the

'lever i4 is pivotally connected at the point 25 arrangement according to Fig. 1, while the distance of the point 24 from the middle of the rock shaft 5 is equal to the length of the lower arm of the said lever.

The operation of the construction illustrated in Fig. 2 is as follows:

On the rocking of the lever I (Fig. 1) there is efiected automatically at the same time the unlocking of the locking bolts (I6, 28) which an.- tomati-cally occupy their terminal positions as securing means. This efiect is realised by reason that, on retraction by the movement of the lever l by way of the link-and-lever connections 2, 3, 4, at first only the cap-like part I3 is rotated about the lug 2| in clockwise direction through the angle on, until the edge 26 of the part l3 abuts on the casing of the locking device.

'During this turning movement the part M is pulled upward and thereby the three-armed lever is turned about its axis 21. By way of the part 22 the part 15 pulls back the locking bolt IS in opposition to the spring 23, whereby the undercarriage is unlocked. At the same time the locking bolt 28 is released by way of the le-- ver 29. On further shift of the link or rod the part l3 operates as an actuating member on the casing l2 and acting by way of the casing turns the'rock shaft 5. rigidly connected with the latter and the undercarriage half 6 in clockwise direction.

As soon'as the undercarriage is retracted, the released locking bolt 28 snaps into the aperture of a guide, not shown, and locks the undercarriage.

Unlocking, retraction, protrusion and locking are thus effected by operation of a single lever l in a single movement of the latter.

The described mode of operation of the devices illustrated in Figs. 1 and 2- is applicable also for the second half of the undercarriage not shown I both for the protruding movements and for the retracting movements.

The invention is not limited to the above described examples of construction. The position and direction of the rock shafts and the direction of rotation on retraction and protrusion of the undercarriage as well as the actuation thereof may be as desired. Instead of the rubber tension member 9, for example springs may be used.

With larger undercarriages, while retaining the fundamental arrangement of the link-and-lever arrangements, by turning the cover sheets, the force of the air stream may be utilized to furnish additional power for the retracting and protruding movements. The actuating mechanism may ultimately be relieved of stresses due to the -masses by the arrangement of the balancing springs in a bufier cylinder.

We claim: A

1. In 'a retractable undergear for aircraft and having a rocking shaft and an actuating lever for rocking said shaft between protracted and retracted positions,'a locking device'for selectively locking said shaft in either of said positions, said locking device comprising a first locking member for locking the shaft in protracted position, a second locking member for locking the shaft in retracted position, a triple armed lever, means coupling said first locking member to one of the arms of said triple armed lever, means coupling said second locking member to a second of the arms of said triple armed lever,

and means coupling the third arm of said triple armed lever with said actuating lever, whereby movement of the actuating lever in one direction will actuate one looking member and release the other locking member.

2. In a device as defined in claim 1, said means coupling the third arm of the three armed lever to the actuating lever including a pivoted member, movement of which by said actuating lever immediately moves said third arm to actuate said locking device, and further movement of which by said actuating member effects rocking said shaft to retracted or protracted position.

3. In a device as defined in claim 1, said means coupling the first and second arms of said triple armed lever including intermediate links between each of said first and second arms of the three armed lever and its corresponding locking member, each of said links having a lost motion connection with its corresponding arm of the three armed lever, and a spring for each locking member urging it in a direction which will take up the slack in said lost motion.

4. In a device as defined in claim 1, said means coupling the first and second arms of said triple armed lever including intermediate links between each of said first and second arms of the three armed lever and its corresponding locking member, each of said links having a 10st motionconnection with its corresponding arm of the three armed lever, and a spring for each locking member urging it in a direction which will take up the slack in said lost motion, said intermediate links being positioned with respect to each other at an angle less than 5. In a retractable undergear for aircraft and having a rocking shaft rotatable to positions in which the undergear will be protracted or retracted; a locking device for selectively locking said rocking shaft in either of said positions, said locking device including, a casing rigidly connected with said shaft, a first locking member in said casing for locking the shaft in retracted position, a second locking member in the casing for locking the shaft in protracted position, a triple armed lever pivotally mounted within said casing, means coupling the first locking member to one of the arms of said triple armed lever, means coupling the second locking member to a second of the arms of said triple armed lever, a cap-like part pivotally connected to said casing and to said actuating lever to be moved thereby so that the edges of said part are capable of two different positions of engagement with said casing to move the casing and hence the shaft to either of its two positions, and link means pivoted to the third arm of said triple armed lever and to said cap-like part, whereby movement of the actuating lever in one direction will actuate one looking member and release the other locking member, and continued movement of the actuating lever in the same direction will rock said shaft.

FRANZ MEYER. FRITZ MAIRE. 

